package com.yunjian.common.utils;

import org.springframework.web.multipart.MultipartFile;

import java.io.*;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5Util {
	/**
	 * 默认的密码字符串组合，用来将字节转换成 16 进制表示的字符,apache校验下载的文件的正确性用的就是默认的这个组合
	 */
	protected static char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
	
	private static final String hexDigit[] = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f"};

	protected static MessageDigest messagedigest = null;
	static {
		try {
			messagedigest = MessageDigest.getInstance("MD5");
		} catch (NoSuchAlgorithmException nsaex) {
			System.err.println(MD5Util.class.getName() + "初始化失败，MessageDigest不支持MD5Util。");
			nsaex.printStackTrace();
		}
	}

	/**
	 * 生成字符串的md5校验值
	 * 
	 * @param s
	 * @return
	 */
	public static String getMD5String(String s) {
		return getMD5String(s.getBytes());
	}

	/**
	 * 判断字符串的md5校验码是否与一个已知的md5码相匹配
	 * 
	 * @param password
	 *            要校验的字符串
	 * @param md5PwdStr
	 *            已知的md5校验码
	 * @return
	 */
	public static boolean checkPassword(String password, String md5PwdStr) {
		String s = getMD5String(password);
		return s.equals(md5PwdStr);
	}

	/**
	 * 生成文件的md5校验值
	 * 
	 * @param file
	 * @return
	 * @throws IOException
	 */
	public static String getFileMD5String(File file) throws IOException {
		InputStream fis;
		fis = new FileInputStream(file);
		byte[] buffer = new byte[1024];
		int numRead = 0;
		while ((numRead = fis.read(buffer)) > 0) {
			messagedigest.update(buffer, 0, numRead);
		}
		fis.close();
		return bufferToHex(messagedigest.digest());
	}

	public static String getMD5String(byte[] bytes) {
		messagedigest.update(bytes);
		return bufferToHex(messagedigest.digest());
	}

	private static String bufferToHex(byte bytes[]) {
		return bufferToHex(bytes, 0, bytes.length);
	}

	private static String bufferToHex(byte bytes[], int m, int n) {
		StringBuffer stringbuffer = new StringBuffer(2 * n);
		int k = m + n;
		for (int l = m; l < k; l++) {
			appendHexPair(bytes[l], stringbuffer);
		}
		return stringbuffer.toString();
	}

	private static void appendHexPair(byte bt, StringBuffer stringbuffer) {
		char c0 = hexDigits[(bt & 0xf0) >> 4];// 取字节中高 4 位的数字转换, >>>
												// 为逻辑右移，将符号位一起右移,此处未发现两种符号有何不同
		char c1 = hexDigits[bt & 0xf];// 取字节中低 4 位的数字转换
		stringbuffer.append(c0);
		stringbuffer.append(c1);
	}
	
	public static String md5Sign(String content) throws NoSuchAlgorithmException, UnsupportedEncodingException {
		String sign;

		MessageDigest md5 = MessageDigest.getInstance("MD5");
		byte[] bytes = md5.digest(content.getBytes("utf-8"));
		sign = encodeBytes(bytes);
		return sign;
	}
	
	public static String encodeBytes(byte[] bytes) {
		StringBuilder hex = new StringBuilder(bytes.length * 2);
		for (byte b : bytes) {
			if ((b & 0xFF) < 0x10) {
				hex.append("0");
			}
			hex.append(Integer.toHexString(b & 0xFF));
		}
		return hex.toString().toUpperCase();
	}
	
	public static String MD5Encode(String origin, String charsetname) {
        String resultString = null;
        try {
            resultString = new String(origin);
            MessageDigest md = MessageDigest.getInstance("MD5");
            if (charsetname == null || "".equals(charsetname))
                resultString = byteArrayToHexString(md.digest(resultString.getBytes()));
            else
                resultString = byteArrayToHexString(md.digest(resultString.getBytes(charsetname)));
        } catch (Exception exception) {
        }
        return resultString;
    }
	
	private static String byteArrayToHexString(byte b[]) {
        StringBuffer resultSb = new StringBuffer();
        for (int i = 0; i < b.length; i++)
            resultSb.append(byteToHexString(b[i]));

        return resultSb.toString();
    }
	
	private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0)
            n += 256;
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigit[d1] + hexDigit[d2];
    }

	public static File multipartFileToFile(MultipartFile file) throws Exception {

		File toFile = null;
		if (file.equals("") || file.getSize() <= 0) {
			file = null;
		} else {
			InputStream ins = null;
			ins = file.getInputStream();
			toFile = new File(file.getOriginalFilename());
			inputStreamToFile(ins, toFile);
			ins.close();
		}
		return toFile;
	}

	private static void inputStreamToFile(InputStream ins, File file) {
		try {
			OutputStream os = new FileOutputStream(file);
			int bytesRead = 0;
			byte[] buffer = new byte[8192];
			while ((bytesRead = ins.read(buffer, 0, 8192)) != -1) {
				os.write(buffer, 0, bytesRead);
			}
			os.close();
			ins.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

}